Grazing increases the temperature sensitivity of soil organic matter decomposition in a temperate grassland

Letter We tested the effects of ungulate grazing and nutrient availability on the temperature sensitivity of soil respiration (CO2) and methane (CH4) emissions in semi-natural temperate grassland. To do this, soil taken from long term grazed and ungrazed grassland was incubated at four temperatures (4, 10, 15 and 20 °C) with two levels of nutrient (NP) addition. The results showed that the variation in soil CO2 and CH4 emissions was explained by temperature and grazing, with grazing increasing the temperature sensitivity of CO2 and CH4 production by between 15 and 20 °C. This response was constrained by nutrient availability for CO2, but not CH4. These findings suggest that grazing could potentially have important impacts on the temperature sensitivity of greenhouse gas emissions in nutrient limited grasslands.